Various attempts are being made to achieve optimal left-right binocular parallax adjustment in stereo cameras having left and right imaging optical systems. For example, an intersection position of optical axes of left and right video cameras is matched with a position of a subject by a steric effect adjustment mechanism using a drive motor, based on focus information. Alternatively, a baseline-length between left and right imaging optical systems of a stereo image imaging device and an angle of convergence are controlled using zoom magnification information, and an appropriate binocular parallax is generated (refer to Patent Document 1 to Patent Document 4).
In addition, a disclosure is made in which a value derived by a baseline-length before change in zoom magnification being multiplied by a reciprocal of the amount of change in the zoom magnification is set as a new baseline-length, and a point of intersection between the optical axes of left and right imaging optical systems is set in an angle of convergence of the same position as that before the change in baseline-length. As a result, the amount of deviation is controlled to differ only slightly from that before the change in zoom, thereby facilitating natural stereo image fusion by an observer (refer to Patent Document 5). Here, natural fusion refers to an observer perceiving an image for the right eye and an image for the left eye as a stereo image.